Interpupillary Distance (IPD) is the distance between the centers of the pupils in each eye. This measurement is used when preparing to make prescription eyeglasses. Positioning lenses correctly in relation to the centre of the pupils is especially important for higher powered lenses due to the location of the optical centre of the lenses.
However, it is very difficult to manually take this measurement against two moving objects (left and right eye) and almost impossible to measure one's own pupillary distance.
As examples of known art, I refer to U.S. Pat. No. 7,322,697 wherein there is disclosed a method of measuring a pupil distance. The method includes locating an imaging device at a position a predetermined distance away from a member attached to eyeglasses worn by a subject. The member has two indicators. The method further includes photographing the subject while the subject observes an observing point in the vicinity of the imaging device, measuring an apparent distance between left and right pupils of the subject on a photographed image, and obtaining an interpupillary distance PD m accordance with: PD=[(A+B).times.C·times.E]/(A.times.D) (1) where “A” represents a distance between the member and the imaging device, “B” represents a distance between a center of rotation of each eye of the subject and the member, “C” represents an actual distance between the indicators in a direction parallel with a line connecting left and right centers of rotation of the subject, “D” represents an apparent distance between the indicators in the direction parallel with the line connecting the left and right centers of rotation on the photographed image, and “E” represents the apparent distance between the left and right pupils of the subject on the photographed image.
Again m U.S. Pat. No. 5,822,032, a device for measuring the interpupillary distance between the pupils of the eyes of that person is disclosed. The device includes a frame having a face and a first hole extending through the frame from the face which is positional at one of the person's two pupils. A disk is mounted juxtaposed to the frame which is rotatable about an axis perpendicular to the frame's face. The disk has a surface and a plurality of second holes extending through the disk from its surface. By rotating the disk, one of the second holes is positional at the other of the person's pupils. The interpupillary distance (IPD) is equal or approximately equal to the distance between the centers of the first and second holes when the holes are positioned at the person's respective pupils.
Again in U.S. Pat. No. 6,535,223, a method for determining the real-world interpupillary distance is provided. The method includes determining the interpupillary distance for a user from an image provided for use with “virtual try-on” technology. This is accomplished by having the user place a reference object on or near their face in the virtual try-on image. The reference object should be one that is a standard size and is readily available to users. Alternatively, the reference object used can be the iris in a user's own eye, since it is well known that the human iris is of a relatively fixed size from individual to individual. When using a reference object, the user takes the facial picture with the reference object on generally the same plane and distance from the camera as their face, such as by holding a quarter on their chin with a single finger. The image is then submitted to the web site as is now standard with sites utilizing virtual try-on technology. After the image is transmitted, the image can then be resized and used to try-on different frames as is known in the prior art. Alternatively, a second image without a reference object can be used for trying on frames. Once the frames are selected and an order for the frames placed, the image with the reference object is associated with the order. The width of the reference object on the image is then compared to the measured interpupillary distance on the image. These measurements can be made in pixels as opposed to real-world distances, because the image is being provided in a pixilated digital file. The actual interpupillary distance can then be calculated by comparing the ratio of the distances measured in the image with the known width of the reference object. Similarly, the virtual interpupillary distance or segment height (usually called “seg height”) needed for multi-focal elements can be determined by measuring the height using the frame on face virtual try-on technology. The measured distance on the image is converted to a real world measurement using the ratio obtained from the reference image.
All of these stated methods and devices/systems and some other methods and devices/systems presently known in the art have had some flaws in design or mechanism and lacks precision. Most of the existing devices are too expensive to be practical for most users. Some shortfalls of the existing methods and systems include manual interference, leading to inaccuracy in measurements. In light of this, there is a need for a method and system that overcomes these constraints.